Hardware engine to demod simo, mimo, and sdma signals

ABSTRACT

An apparatus including a configurable demodulation architecture which includes a control module and a demodulation engine. The control module includes a set of one or more control fields. The demodulation engine includes a spatial whitening module, a Minimum Mean Square Estimation (MMSE) module, at least a first Maximal Ratio Combining (MRC) module, and at least one multiplexer. Further, the multiplexer is coupled to the instruction module and controlled based on the control fields to select at least one of the MMSE module or MRC module.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present application for Patent claims priority to ProvisionalApplication No. 61/040,307 entitled “HARDWARE ENGINE TO DEMOD SIMO, MIMOAND SDMA SIGNALS” filed Mar. 28, 2008 and Provisional Application No.61/040,462 entitled “CONFIGURATION FOR IMPLEMENTING A TASKLIST PROVIDINGPROCESSING OF WHITENED SIGNALS” filed Mar. 28, 2008, and assigned to theassignee hereof and hereby expressly incorporated by reference herein.

FIELD OF DISCLOSURE

The invention relates to communications in a telecommunications system,and more particularly to a hardware engine to demodulate Single InputMultiple Output (SIMO), Multiple Input Multiple Output (MIMO) and SpaceDiversity Multiple Access (SDMA) signals in a telecommunications system.

BACKGROUND

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, and so on. Thesesystems may be multiple-access systems capable of supportingcommunication with multiple users by sharing the available systemresources (e.g., bandwidth and transmit power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, 3rd Generation PartnershipProject (3GPP) Long Term Evolution (LTE) systems, and orthogonalfrequency division multiple access (OFDMA) systems.

Generally, a wireless multiple-access communication system cansimultaneously support communication for multiple wireless terminals.Each terminal communicates with one or more base stations viatransmissions on the forward and reverse links. The forward link (ordownlink) refers to the communication link from the base stations to theterminals, and the reverse link (or uplink) refers to the communicationlink from the terminals to the base stations. This communication linkmay be established via a single-in-single-out, multiple-in-signal-out ora multiple-in-multiple-out (MIMO) system.

A MIMO system employs multiple (N_(T)) transmit antennas and multiple(N_(R)) receive antennas for data transmission. A MIMO channel formed bythe N_(T) transmit and N_(R) receive antennas may be decomposed intoN_(S) independent channels, which are also referred to as spatialchannels; where N_(S)≦min{N_(T), N_(R)}. Each of the N_(S) independentchannels corresponds to a dimension. The MIMO system can provideimproved performance (e.g., higher throughput and/or greaterreliability) if the additional dimensionalities created by the multipletransmit and receive antennas are utilized.

A MIMO system supports time division duplex (TDD) and frequency divisionduplex (FDD) systems. In a TDD system, the forward and reverse linktransmissions are on the same frequency region so that the reciprocityprinciple allows the estimation of the forward link channel from thereverse link channel. This enables the access point to extract transmitbeam-forming gain on the forward link when multiple antennas areavailable at the access point. Furthermore, a wide variety oftransmit/receive methodologies currently exist using multiple channels,such as, for example, MIMO, SIMO, SDMA, Space-time block coding basedtransmit diversity (STTD, Space-frequency block coding based transmitdiversity (SFTD), etc. Each of these methodologies has varioussituational advantages and disadvantages. However, currently existingwireless devices may lack the ability to utilize all of thesemethodologies in a streamlined manner.

Accordingly, there is a need for new architectures and processes whichcan flexibly utilize a wide variety of these multi-channeltransmit/receive technologies. Moreover, by preprocessing symbols priorto modulation, the efficiency of multi-channel demodulation techniquescan be improved.

SUMMARY

Exemplary embodiments of the invention are directed to systems andmethods for demodulation operations.

Accordingly an embodiment can include a an apparatus including aconfigurable demodulation architecture comprising: a control moduleincluding a set of one or more control fields; and a demodulation engineincluding; a spatial whitening module; a Minimum Mean Square Estimation(MMSE) module; at least a first Maximal Ratio Combining (MRC) module;and at least one multiplexer coupled to the instruction module andcontrolled based on the control fields to select at least one of theMMSE module or MRC module.

Another embodiment can include a method for performing demodulationoperations, the method comprising: establishing a set of one or morecontrol fields; performing a spatial whitening operation on input data;filtering the whitened input data using at least one of Minimum MeanSquare Estimation (MMSE) or Maximal Ratio Combining (MRC); and selectingthe MMSE or MRC filtering based on the control fields to producedemodulation data from the whitened input data.

Another embodiment can include a computer-readable medium comprisinginstructions which, when executed by at least one processor, operates toprovide processing of communication signals, the computer-readablemedium comprising: instructions to establish a set of one or morecontrol fields; instructions to perform a spatial whitening operation oninput data; instructions to filter the whitened input data using atleast one of Minimum Mean Square Estimation (MMSE) or Maximal RatioCombining (MRC); and instructions to select the MMSE or MRC filteringbased on the control fields to produce demodulation data from thewhitened input data.

Another embodiment can include an apparatus in a wireless communicationssystem, the apparatus comprising: means for establishing a set of one ormore control fields; means for performing a spatial whitening operationon input data; means for filtering the whitened input data using atleast one of Minimum Mean Square Estimation (MMSE) or Maximal RatioCombining (MRC); and means for selecting the MMSE or MRC filtering basedon the control fields to produce demodulation data from the whitenedinput data.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofembodiments of the invention and are provided solely for illustration ofthe embodiments and not limitation thereof.

FIG. 1 illustrates a multiple access wireless communication systemaccording to one embodiment;

FIG. 2 is a block diagram of an exemplary communication system;

FIG. 3 is a block diagram of an exemplary transmission architecture forarranging packets of data.

FIG. 4 depicts an exemplary logical arrangement of OFDM data.

FIG. 5 depicts an exemplary hardware receiver architecture withsupporting processor.

FIG. 6 is a schematic block diagram showing a relationship between anexemplary processing system and an MMSE/MRC processing engine.

FIG. 7 is a schematic block diagram showing channel estimationimplemented using MMSE and MRC with a whitening engine.

FIG. 8 depicts a flowchart showing an exemplary process performed by anembodiment of the hardware architecture.

DETAILED DESCRIPTION

Aspects of the invention are disclosed in the following description andrelated drawings directed to specific embodiments of the invention.Alternate embodiments may be devised without departing from the scope ofthe invention. Additionally, well-known elements of the invention willnot be described in detail or will be omitted so as not to obscure therelevant details of the invention.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. Likewise, the term “embodiments ofthe invention” does not require that all embodiments of the inventioninclude the discussed feature, advantage or mode of operation.

The techniques described herein may be used for various wirelesscommunication networks such as Code Division Multiple Access (CDMA)networks, Time Division Multiple Access (TDMA) networks, FrequencyDivision Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA)networks, Single-Carrier FDMA (SC-FDMA) networks, etc. The terms“networks” and “systems” are often used interchangeably. A CDMA networkmay implement a radio technology such as Universal Terrestrial RadioAccess (UTRA), cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA) andLow Chip Rate (LCR). cdma2000 covers IS-2000, IS-95 and IS-856standards. A TDMA network may implement a radio technology such asGlobal System for Mobile Communications (GSM). An OFDMA network mayimplement a radio technology such as Evolved UTRA (E-UTRA), IEEE 802.11,IEEE 802.16, IEEE 802.20, Flash-OFDM®, etc. UTRA, E-UTRA, and GSM arepart of Universal Mobile Telecommunication System (UMTS). Long TermEvolution (LTE) is an upcoming release of UMTS that uses E-UTRA. UTRA,E-UTRA, GSM, UMTS and LTE are described in documents from anorganization named “3rd Generation Partnership Project” (3GPP). cdma2000is described in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). These various radio technologies andstandards are known in the art. For clarity, certain aspects of thetechniques are described below for LTE, and LTE terminology is used inmuch of the description below.

Single carrier frequency division multiple access (SC-FDMA), whichutilizes single carrier modulation and frequency domain equalization, isa technique that has similar performance and essentially the sameoverall complexity as that of an OFDMA system. SC-FDMA signals have alower peak-to-average power ratio (PAPR) because of its inherent singlecarrier structure. SC-FDMA has drawn great attention; especiallyregarding uplink communications where a lower PAPR greatly benefits themobile terminal in terms of transmit power efficiency. Currently, it isa working assumption for an uplink multiple access scheme in 3GPP LongTerm Evolution (LTE), or Evolved UTRA that SC-FDMA be utilized.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of embodiments ofthe invention.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”,“comprising,”, “includes” and/or “including”, when used herein, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Further, many embodiments are described in terms of sequences of actionsto be performed by, for example, elements of a computing device. It willbe recognized that various actions described herein can be performed byspecific circuits (e.g., application specific integrated circuits(ASICs)), by program instructions being executed by one or moreprocessors, or by a combination of both. Additionally, these sequence ofactions described herein can be considered to be embodied entirelywithin any form of computer readable storage medium having storedtherein a corresponding set of computer instructions that upon executionwould cause an associated processor to perform the functionalitydescribed herein. Thus, the various aspects of the invention may beembodied in a number of different forms, all of which have beencontemplated to be within the scope of the claimed subject matter. Inaddition, for each of the embodiments described herein, thecorresponding form of any such embodiments may be described herein as,for example, “logic configured to” perform the described action.

Referring to FIG. 1, a multiple access wireless communication systemaccording to one embodiment is illustrated. An access point 100 (AP)includes multiple antenna groups; one including antenna elements 104 and106, another including antenna elements 108 and 110, and an additionalincluding antenna elements 112 and 114. In FIG. 1, only two antennas areshown for each antenna group, however it is understood by one ofordinary skill in the art, that more or fewer antennas may be utilizedfor each antenna group. Access terminal 116 (AT) is in communicationwith antenna elements 112 and 114, where antenna elements 112 and 114transmit information to access terminal 116 over forward link 120 andreceive information from access terminal 116 over reverse link 118.Access terminal 122 is in communication with antenna elements 106 and108, whereas antenna elements 106 and 108 transmit information to accessterminal 122 over forward link 126 and receive information from accessterminal 122 over reverse link 124. In a FDD system, communication links118, 120, 124 and 126 may use different frequency for communication. Forexample, forward link 120 may use a different frequency than that usedby reverse link 118.

Each group of antennas and/or the area in which they are designed tocommunicate is often referred to as a sector of the access point. In theembodiment, antenna groups each are designed to communicate to accessterminals in a sector, of the areas covered by access point 100.

In communication over forward links 120 and 126, the transmittingantennas of access point 100 may utilize beamforming in order to improvethe signal-to-noise ratio of forward links for the different accessterminals 116 and 124. Also, an access point using beamforming totransmit to access terminals, scattered randomly through its coveragearea, can cause less interference to access terminals in neighboringcells than an access point transmitting through a single antenna to allits access terminals.

An access point may be a fixed station used for communicating with theterminals and may also be referred to as an access point, a Node B, orsome other terminology. An access terminal may also be called an accessterminal, user equipment (UE), a wireless communication device,terminal, access terminal or some other terminology.

FIG. 2 is a block diagram of an embodiment of an AP 210 (also known asthe access point) and an AT 250 (also known as access terminal) in aMIMO system 200. At the AP 210, traffic data for a number of datastreams is provided from a data source 212 to a transmit (TX) dataprocessor 214.

In an embodiment, each data stream is transmitted over a respectivetransmit antenna. TX data processor 214 formats, codes, and interleavesthe traffic data for each data stream based on a particular codingscheme selected for that data stream to provide coded data.

The coded data for each data stream may be multiplexed with pilot datausing OFDM techniques. The pilot data is typically a known data patternthat is processed in a known manner and may be used at the receiversystem to estimate the channel response. The multiplexed pilot and codeddata for each data stream is then modulated (i.e., symbol mapped) basedon a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM)selected for that data stream to provide modulation symbols. The datarate, coding, and modulation for each data stream may be determined byinstructions performed by processor 230.

The modulation symbols for all data streams are then provided to a TXMIMO processor 220, which may further process the modulation symbols(e.g., for OFDM). TX MIMO processor 220 then provides N_(T) modulationsymbol streams to N_(T) transmitters (TMTR) 222 a through 222 t. Incertain embodiments, TX MIMO processor 220 applies beamforming weightsto the symbols of the data streams and to the antenna from which thesymbol is being transmitted.

Each transmitter 222 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel. N_(T)modulated signals from transmitters 222 a through 222 t are thentransmitted from N_(T) antennas 224 a through 224 t, respectively.

At AT 250, the transmitted modulated signals are received by N_(R)antennas 252 a through 252 r and the received signal from each antenna252 is provided to a respective receiver (RCVR) 254 a through 254 r.Each receiver 254 conditions (e.g., filters, amplifies, anddownconverts) a respective received signal, digitizes the conditionedsignal to provide samples, and further processes the samples to providea corresponding “received” symbol stream.

An RX data processor 260 then receives and processes the N_(R) receivedsymbol streams from the N_(R) receivers 254 based on a particularreceiver processing technique to provide N_(T) “detected” symbolstreams. The RX data processor 260 then demodulates, deinterleaves, anddecodes each detected symbol stream to recover the traffic data for thedata stream. The processing by RX data processor 260 is complementary tothat performed by TX MIMO processor 220 and TX data processor 214 at AP210.

A processor 270 provides control to the AT 250 and provides an interfaceto memory 272, RX Data processor 260 and TX Data processor 238. A TXdata processor 238 receives traffic data for a number of data streamsfrom a data source 236, modulated by a modulator 280, conditioned bytransmitters 254 a through 254 r, and transmitted back to AP 210.

At AP 210, the modulated signals from AT 250 are received by antennas224, conditioned by receivers 222, demodulated by a demodulator 240, andprocessed by a RX data processor 242 to extract the reverse link messagetransmitted by the AT 250. A processor 230 provides control to the AP210 and provides an interface to memory 232, TX Data processor 214 andTX MIMO Processor 220.

FIG. 3 depicts an exemplary transmitting architecture 300. As suggestedin FIG. 3, a packet of information Input Packet 301 can be split into anumber of sub-packets {a, b, c, . . . }. Afterwards, each sub-packet isreceived by blocks 321 a-321 c. Blocks 321 a-321 c may perform a numberof standard processes. For example, a Cyclic Redundancy Check (CRC)checksum, encoding, channel interleaving, sequence repetition and datascrambling. The resultant processed sub-packets may then be combinedinto a larger architecture (described further below), then modulated byModulator 331 and then transmitted according to an OFDM scheme, andtransmitted according to a temporal architecture of frames andsuper-frames.

For various blocks of data in a frame/super-frame architecture, OFDMsignals and data may be organized into sub-blocks, called “tiles” inthis disclosure. These tiles may be generated in the receivers shown inFIGS. 5, 6 and 7. FIG. 4 shows an example of an OFDM signal broken into128 tiles; with each tile being made from 16 separate tones (orsub-channels) over 8 OFDM symbols such that each tile may consist of asmany as 128 symbols. The format of FIG. 4 shows an OFDM physical layerthat provides a 3-D time-frequency-space grid that may be used accordingto a Block Hopping Mode where some of these tiles may are assigned to anAT.

As shown in FIG. 4, each of the various tiles can have both data symbolsand pilot symbols, with data symbols being used to carry information andpilot symbols being used to perform a wide variety of tasks, some ofwhich may be explained further below, noting that an orthogonal pilotsequence from an AP Tx antenna can allow channel and interferenceestimation per layer.

Again, non-pilot symbols can be occupied by data from severalsubpackets, where symbols from a subset of subpackets are “painted” onnon-pilot tones in a round-robin fashion across one or more tiles.

Depending on a desired assignment of tiles to data, payload data may beeffectively arranged. For example, in FIG. 4 tile 127 is assigned tohold three sub-packets of information {a, b, c} with sub-packet {a}containing data symbols (a0, a1, a2, a3 . . . }, sub-packet {b}containing data symbols (b0, b1, b2, b3 . . . }, and sub-packet {c}containing data symbols (c0, c1, c2, c3 . . . }. However, thisarrangement of sub-packet data within a tile is exemplary and does notpreclude other arrangement patterns. Note that the various symbols thatare interspersed together on tile 127 in a process/format may bereferred to as sub-packetization or “painting.” Sub-packetization mayallow for the pipelining of demodulation and decoding operations fordifferent sub-packets. In this context, pipelining may refer to theconcurrent operation of the demodulation operation on a tile while thedecoding operation can happen on a sub-packet, which can span tiles thatmay already have been demodulated. Furthermore, it is noted that thesub-packets of information contained within the tiles shown in FIG. 4may vary. For example, in one embodiment the tiles may containinformation pertaining to demodulated data (I, Q, SNR) for eachsymbol/tone combination. However, in another embodiment, the tiles maycontain information pertaining to channel interpolation/estimation data(for example, channel estimation coefficients).

FIG. 5 depicts an exemplary hardware receiver architecture 503 withsupporting processor. As shown in FIG. 5, two antennas AN_(T) 0 andAN_(T) 1 are shown leading to an analog front-end 501, which may performvarious processes on the received signals, such as buffering, filtering,mixing and analog to digital conversion (ADC) to provide two streams ofdigitized data to a digital front-end of the hardware receiverarchitecture 505.

The digital front-end of the hardware receiver architecture 505 canprocess the received data including such processes, as DC offsetcorrection, digital filtering, IQ correction, frequency correction anddigital gain control. The digital front-end 505 may then provide thedigitally processed data as dual data streams to the FFT sampleserver/engine 507, which in turn may process the OFDM data using FFTs(or DFTs) under control of Controller 515, which may be any form ofsequential instruction processing machine executing software/firmware.Further, FFT sample server/engine 507 may include a sample server and asymbol buffer 507 a.

Controller 515 may perform channel estimation. It is well known that awireless channel may introduce arbitrary time dispersion, attenuation,and phase shift in a received signal over a communications channel.Channel estimation may be used to form an estimate of the time,amplitude and/or phase shift caused by the wireless channel from theavailable pilot information. Channel estimation may remove the effect ofthe wireless channel and allows subsequent symbol demodulation. Channelestimation may be implemented by any number of different algorithms.Controller 515 receives pilot data from FFT sample server/engine 507,which can be stored in Symbol Buffer 507 a. Further, Controller 515sends channel estimation data and noise variance data to DemodDevice/Engine 509.

The FFT symbol data of the FFT sample server/engine 507 may then beprovided to the Demod Engine 509, which may perform any number ofdemodulation operations, such as channel interpolation 509 a, MaximumRatio Combining (MRC)/Minimum Mean Square Error (MMSE) operations 509 b,to produce dual demodulated outputs with each output arranged logicallyin a manner consistent with the tiles of FIG. 4. Note that each entry ofeach tile output by the Demod Engine 509 may include three componentsincluding a real portion (I), an complex portion (Q) and a related SNR.Further, in one embodiment a Buffer 510 may be positioned after theDemod Engine 509.

The outputs of the Buffer 510 may be further processed by Demap Engine511 and Decode Engine 513 in manners more fully discussed below. TheDemap Engine 511 may include a log-likelihood ratio (LLR) engine 511 athat can convert I, Q and SNR data to soft bits. Further, the DemapEngine 511 can reorder the data format from tile-based to packet-based.The exemplary Demap Engine 511 may include a log-likelihood ratio (LLR)engine 511 a, a sub-packetization engine, a descrambler and ade-interleaver. The LLR Engine 511 a can be responsible for generatingLog-Likelihood-Ratios, which may convey the soft informationneeded/useable by the Decode Engine 513. In the present embodiment, LLRsmay be generated independently for two layers in MIMO arrangements. Theinputs may include demodulated I, Q, and SNR data—per layer for eachtone and Modulation Order. The output may include Log-Likelihood-Ratios(LLRs) for 2-bit data (QPSK), 3-bit data (8PSK), 4-bit data (16 QAM)and/or 6-bit data (64 QAM).

The Decode Engine 513 may include an LLR Buffer, a Turbo Decoder and aViterbi Decoder. The Decode Engine 513 performs the basic operations ofa standard decoder. The Turbo Decoder may include Turbo Codes/Decodersthat are high-performance error correction codes to achieve maximalinformation transfer over a limited-bandwidth communication link in thepresence of data-corrupting noise. The Viterbi Decoder may use theViterbi algorithm for decoding a bitstream that has been encoded usingforward error correction based on a Convolutional code.

While the embodiment of receiver 503 was shown using only two receiveantennas ANT-0 and ANT-1, it is understood that this arrangement ismerely exemplary and in no way should it be considered as restrictive.Various embodiments of the invention may use any plurality of receiveantennas/channels FIG. 6 is a schematic block diagram showing arelationship between an exemplary processing system and an MMSE/MRCprocessing engine, such as that portrayed in the Demod Engine 509 ofFIG. 5. As shown in FIG. 6, the processing system may include aninstruction processor (DSP) 620, input data symbol buffer 630, anMMSE/MRC control block 640 and a corresponding engine 650, and an outputbuffer 670.

The instruction processor 620 may include a protocol determinationdevice 624, a channel estimation whitening device 626 and a task list628. In operation, the instruction processor 620 can determine thenumber of transmit antennas used by a transmitting AP via the protocoldetermination device 624, and further determines various aspects of theprotocol of received signals. The protocol determination device 624 mayalso determine the type of traffic assignment that is utilized via theuse of a control packet. The protocol determination device 624 can alsodetermine the type of modulation utilized and whether MIMO, SIMO or SDMAis utilized. Further, the protocol determination device 624 may alsodetermine whether MMSE or MRC is utilized.

The channel estimation whitening device 626 can calculate noisewhitening computations based upon channel estimate data and pilot data.Further, the channel estimation whitening device 626 can accommodateMMSE/MRC processing. In various protocols, for example such as in anUltra Mobile Broadband (UMB) system, the Forward Link (FL) transmissionscan be sent in Single Input Multiple Output (SIMO) mode or MIMO mode,and the UMB-AT may use MRC or MMSE processing to respectively demodulatesuch signals. As MMSE and MRC demod algorithms are computationallyintensive, care is taken to optimize their complexity for HWimplementation in order to save area and power. Further, thesealgorithms can be simplified (up to 50% reduction in complex multiplies)if the noise across the multiple receive antennas is assumed to beuncorrelated. However in practice, since the noise across the receiveantennas is correlated, this is not often achievable. As a result, inorder to correct for the correlated noise, the channel estimationwhitening device 626 can perform the following operations: 1) compute aspatial correlation matrix for a received signal, 2) compute arespective “whitening transform”, and 3) whiten the resultant channelestimates. Furthermore, the actual data may be whitened in the Demodhardware using the whitened channel estimates.

As shown in FIG. 6, the whitened channel estimates 620 a, as well as atask list (control) information 620 b, may be provided to the MMSE/MRCengine 650 via MMSE/MRC control device 640.

The MMSE/MRC task list 628 is a number of parameters that the firmwaremay collect/process that can be passed to the hardware in order toperform demodulation. According to the above architecture, any number ofinstructions, variables, and/or data may be held in the MMSE and MRCEngine Task List 628 for use by the MMSE and MRC control block 640. Asnon-limiting examples, the MMSE and MRC Engine Task List 628 mayinclude: variable(s) representing a sample start address, instructionsfor reading or supplying a sample start address of buffer 630,information as to the number of transmit antennas used, informationregarding signal protocol, information regarding the type of transmitmode used, information regarding whether MMSC or MRC is enabled,information regarding the modulation order (i.e. for 64-QAM is 6 bitsper symbol, for 8PSK is 3 bits per symbol and for QPSK is 2 bits persymbol), information regarding the number of transmitters that areutilized, and anything else that may be used in order to perform MMSE orMRC. The contents of the MMSE and MRC Engine Task List 628 may be heldin firmware or memory, and may be updated and modified with new ordifferent instructions, variables, and/or data as needed. Note that theinstructions, variables, and or data held in the MMSE and MRC EngineTask List 628 can be requested by the MMSE and MRC control block 640 andstored in registers therein, or can be pushed into the MMSE and MRCcontrol block 640 by the instruction processor 620.

The MMSE/MRC control block 640 receives a task list from informationprocessor 620 and feeds numerous parameter inputs to the MMSE/MRC engine650. As non-limiting examples, the parameters passed to the MMSE/MRCengine 650 may include: a scaling factor, β (discussed below) whichreduces bitwidths, whitening coefficients, correlation matrix (R_(vv))obtained from the instruction processor 620 (discussed below), and aCholesky factorization based on a whitening transform, W=R_(v/v) ^(−1/2)(discussed below).

The MMSE/MRC engine 650 receives various parameters from the MMSE/MRCcontrol block 640.

During an exemplary operation, symbol buffer 630 receives sample data601 and provides an output to MMSE/MRC engine 650. The symbol buffer 630may contain data (frequency domain) and be similar in function to thatshown in FIG. 4. For example, each tile may contain 8 symbols and 16tones, where the tiles are filled with tones and pilot data.

The MMSE/MRC engine 650 can use the noise whitening information 620 aand control information 620 b from instruction processor 620 (viaMMSE/MRC control block 640) in order to whiten the data provided by thedata symbol buffer 630. The MMSE/MRC engine 650 provides an output tooutput buffer 670.

The output buffer 670 receives demodulated data from MMSC/MRC engine650. The output buffer 670 may contain data (I, Q and SNR) and besimilar in function as to that shown in FIG. 4. Furthermore, the outputbuffer 670 may be contained within demod device 509 (not shown).

Further, the radio architecture shown in FIG. 6 may be utilized foreither MMSE or MRC functions. Specifically, MMSE/MRC engine 650 may beutilized for either MMSE or MRC even though the MMSE and MRC methodsboth compute different filter computations (shown below). As a result,the radio architecture shown in FIG. 6 is flexible and allows for theoperation of various multichannel transmit/receive methodologies,including both MIMO and SIMO estimations.

FIG. 7 is a schematic block diagram showing channel estimationimplemented using MMSE and MRC with a whitening engine. Thisarchitecture can be useful for various multichannel transmit/receivemethodologies, including both MIMO estimations and SIMO estimations.

In operation, DSP 620 can provide information to demodulation taskcontrol registers 717, and channel interpolation engine 719.

The channel interpolation engine 719 may provide a channel estimate (h₁,h₂) per tone to MMSE/MRC engine 650.

The spatial whitening device 721 can receive the whitening channelestimates (W, β²), and whitens the FFT data (ŷ₁, ŷ₂) received from FFTsymbol buffer 630 using the whitened channel estimates (W, β²),whereafter the following components may perform MMSE or MRC estimationusing the whitened FFT data (y₁, y₂).

The overall process of whitening and estimating is outlined in theequations below.

The signal model for a tone transmitted on two transmit antennas andreceived on two receive antennas is:

ŷ=Ĥs+v  Equation (2a)

where:

ŷ=[ŷ₁ ŷ₂]^(T)  Equation (2b)

is the received data vector;

s=[s₁ s₂]^(T)  Equation (2c)

is the vector symbol that is to be demodulated;

$\begin{matrix}{\overset{\Cap}{H} = {\left\lbrack {{\overset{\Cap}{h}}_{1}\mspace{14mu} {\overset{\Cap}{h}}_{2}} \right\rbrack = \begin{bmatrix}{\overset{\Cap}{h}}_{11} & {\overset{\Cap}{h}}_{12} \\{\overset{\Cap}{h}}_{21} & {\overset{\Cap}{h}}_{22}\end{bmatrix}}} & {{Equation}\mspace{14mu} \left( {2d} \right)}\end{matrix}$

is the estimated channel matrix;

v=[v₁ v₂]^(T)  Equation (2e)

is the noise vector observed at the receive antennae with a correlationmatrix, R_(vv), obtained from the instruction processor 620;

$\begin{matrix}{R_{vv} = \begin{bmatrix}\sigma_{1}^{2} & {\rho \; \sigma_{1}\sigma_{2}} \\{\rho^{*}\sigma_{1}\sigma_{2}} & \sigma_{2}^{2}\end{bmatrix}} & {{Equation}\mspace{14mu} (3)} \\{W = {\beta {\frac{1}{\sqrt{1 - {\rho }^{2}}\sigma_{1}\sigma_{2}}\begin{bmatrix}{\sqrt{1 - {\rho }^{2}}\sigma_{2}} & 0 \\{{- \rho^{*}}\sigma_{2}} & \sigma_{1}\end{bmatrix}}}} & {{Equation}\mspace{14mu} (4)}\end{matrix}$

is the Cholesky factorization based on the whitening transform, W=R_(vv)^(−1/2) β is a scaling introduced to reduce bitwidths.

An operation to pre-whiten the input (ŷ₁, ŷ₂) and channel estimate (h₁,h₂) is performed to simplify computation according to: (1) MMSE withpre-whitening 20-Complex Multiplies+2-Real Divides; and (2) MMSE withoutpre-whitening 32-Complex Multiplies+5-Real Divides.

The operation to pre-whiten the input signal (ŷ₁, ŷ₂) and channelestimate (h₁, h₂) is performed by:

y=Wŷ and H=WĤ  Equation (5)

MMSE filter:

$\begin{matrix}{f_{1} = \left\lbrack {h_{1} - {h_{2}\frac{h_{2}^{*}h_{1}}{1 - {h_{2}}^{2}}}} \right\rbrack^{T}} & {{Equation}\mspace{14mu} (6)}\end{matrix}$

to swap indexes 1 and 2 for f₂

Bias:

$\begin{matrix}{g_{1} = \left\lbrack {{h_{1}} - \frac{{{h_{2}^{*}h_{1}}}^{2}}{1 + {h_{2}}^{2}}} \right\rbrack^{T}} & {{Equation}\mspace{14mu} (7)}\end{matrix}$

to swap indexes 1 and 2 for g₂

Interference:

σ_(k) ²=g_(k)  Equation (8)

Demod SNR:

$\begin{matrix}{{SNR}_{k} = {\frac{g_{k}^{2}}{\sigma_{k}^{2}} = g_{k}}} & {{Equation}\mspace{14mu} (9)}\end{matrix}$

Demod Symbol:

ŝ_(k)=f*_(k)y  Equation (10)

LLR Component:

L(s _(k))=s _(k)(s _(k)SNR_(k)−2ŝ _(k))  Equation (11)

Returning to FIG. 7, the channel interpolation engine 719 interfaceswith MRC filter computation 731 and 732 and MMSE filter computation 738.

MMSE filter computation 738 performs MMSE filter computation inaccordance with the filter of equation 6.

MRC filter computation 731 and 732 perform MRC filter computation inaccordance with the filter of equation 6. However, the estimated channelmatrix for MRC operations contains an h₂ value equal to 0.

Multiplexers 741 and 742 can direct the appropriate data flow from MRCfilter computation devices 731 and 732 and MMSE filter computationdevice 738. The output of multiplexers 741, 742 is connected to SNRcomputation device 761, 762 and demod symbol computation device 781,782. Multiplexers 741, 742 are controlled by the control fields producedby demodulation task control registers 717 such that the demodulationdata is at least based on computations from either of the MMSE and MRCcircuits.

SNR computation devices 761, 762 compute the SNR (SNR₁, SNR₂) of thereceived signal from the multiplexers 741, 742 in accordance withequation 9. The SNR computation devices 761, 762 receive a channelestimate (h₁, h₂) from channel interpolation engine 719 and data fromthe multiplexers 741, 742.

The demod symbol computation devices 781, 782 compute the demodulatedsymbols (ŝ₁, ŝ₂) from the multiplexers 741, 742 in accordance withequation 10. The demod symbol computation devices 781, 782 receivewhitened FFT data (y₁, y₂) and data from the multiplexers 741, 742.

An LLR block 511 a may demap the symbol to a soft bit via use ofequation 11 and the demodulated symbols (ŝ₁, ŝ₂) and SNR (SNR₁, SNR₂) ofthe received signal.

Accordingly, various modes of operation can be implemented dependentupon the operation of ports 1 and 2. However, it is understood that thisis an exemplary illustration and that a plurality of ports may beutilized.

The device shown in FIG. 7 can operate in MMSE mode when the data isextracted from both Ports 1 and Port 2 every cycle.

The device shown in FIG. 7 can operate in MRC mode when the data isextracted from Port 2 every cycle.

The device shown in FIG. 7 can operate in SDMA mode when the MMSE/MRCengine 650 is run in the same manner as for MMSE, however, the data isextracted from alternating ports (1 and 2).

The device shown in FIG. 7 can operate in STTD mode when the MMSE/MRCengine 650 is run in the same manner as for MMSE, however, the data isextracted from ports 1 and 2 by combining them in post-processing.

The device shown in FIG. 7 can operate in SFTD mode when the MMSE/MRCengine 650 is run in the same manner as for MMSE, however, the data isextracted from ports 1 and 2 by combining them in post-processing.

Furthermore it is noted that when not in use, MRC filter devices 731,732 and MMSE filter device 738 may be disabled and/or de-powered forenergy savings.

While the embodiment shown in FIG. 7 was shown using only two outputports PORT 1 and PORT 2, it is understood that this arrangement ismerely exemplary and in no way should it be considered as restrictive.Various embodiments of the invention may use any plurality of outputports.

FIG. 8 is a flowchart showing an exemplary process 800 that may beperformed by an embodiment of the hardware architecture such asillustrated in FIGS. 6 and 7.

Initially, the DSP 620 may establish a set of one or more controlfields, and then provide them to the Demod Task Control Register 717.(Block 805). Additionally, the DSP 620 may also generate whiteningparameters (e.g., W, β²) as described above. The whitening parametersmay be provided to the spatial whitening module 721, which resides inthe MMSE/MRC Engine 650. The spatial whitening module 721 may alsoreceive the input data (e.g., ŷ₁, ŷ₂), and in conjunction with thewhitening parameters, process the input data in order to producewhitened FFT data (e.g., y₁, y₂) (Block 810). Additionally, the channelestimate channel estimate (h₁, h₂) may also undergo pre-whiteningoperation.

Filter coefficients corresponding to MRC and/or MMSE can then becomputed in MRC Filter Computation modules 731 and 732, and MMSE FilterComputation module 738, respectively. The whitened data (e.g., y₁, y₂)may then be filtered using the MMSE and/or the MRC coefficients (Block815). The MMSE and/or MRC filtering may be selected, based upon thecontrol fields, to produce demodulated data (e.g., ŝ₁, ŝ₂), which may becomputed by the Demod Symbol Computation device 761 and/or 782. (Block820). The selection may be performed by multiplexers 741 and/or 742based upon the control fields provided by the Demod Task Register 717.The SNR associated with the demodulated data may be computed by SNRcomputation devices 761 and 762, using data provided by multiplexers 741and/or 742, and the channel estimates provided by the channelinterpolation engine 719.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is part of an example of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged while remainingwithin the scope of the present disclosure. The accompanying methodclaims present elements of the various steps in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The methods, sequences and/or algorithms described in connection withthe embodiments disclosed herein may be embodied directly in hardware,in a software module executed by a processor, or in a combination of thetwo. A software module may reside in RAM memory, flash memory, ROMmemory, EPROM memory, EEPROM memory, registers, hard disk, a removabledisk, a CD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor.

Accordingly, an embodiment of the invention can include a computerreadable media embodying a method for the processing of communicationsignals, the computer-readable medium including instructions toestablish a set of one or more control fields, instructions to establisha sequential instruction logic which is capable of processing softwarecommands, instructions to provide filtering according to at least one ofMinimum Mean Square Estimation (MMSE) and Maximal Ratio Combining (MRC),instructions to multiplex the output of the filtering, instructions tocontrol the multiplex operation by the control fields for producingdemodulation data based on computations from either of the MMSE and MRClogic to produce a plurality of signals. Accordingly, the invention isnot limited to illustrated examples and any means for performing thefunctionality described herein are included in embodiments of theinvention.

While the foregoing disclosure shows illustrative embodiments of theinvention, it should be noted that various changes and modificationscould be made herein without departing from the scope of the inventionas defined by the appended claims. The functions, steps and/or actionsof the method claims in accordance with the embodiments of the inventiondescribed herein need not be performed in any particular order.Furthermore, although elements of the invention may be described orclaimed in the singular, the plural is contemplated unless limitation tothe singular is explicitly stated.

1. An apparatus including a configurable demodulation architecturecomprising: a control module including a set of one or more controlfields; and a demodulation engine including: a spatial whitening module;a Minimum Mean Square Estimation (MMSE) module; at least a first MaximalRatio Combining (MRC) module; and at least one multiplexer coupled tothe instruction module and controlled based on the control fields toselect at least one of the MMSE module or MRC module.
 2. The apparatusof claim 1, wherein the demodulation engine is configured to receiveconfiguration information including control data and whitening channelestimates from a task list via the control module, and to performdemodulation according to a demodulation scheme on a serial stream ofdata.
 3. The apparatus of claim 2, wherein the stream of data is derivedfrom a Multiple Input Multiple Output (MIMO) signal and MMSE data isprovided to output Port 1 and output Port 2 every cycle.
 4. Theapparatus of claim 1, further comprising a plurality of output ports. 5.The apparatus of claim 4, wherein the plurality of output ports includesa first output port (Port 1) and a second output port (Port 2).
 6. Theapparatus of claim 5, wherein MRC data is provided to at least one portevery cycle.
 7. The apparatus of claim 5, wherein Spatial-DivisionMedium Access (SDMA) data is provided to alternating ports.
 8. Theapparatus of claim 5, wherein at least one of Space-time block codingbased transmit diversity (STTD) or Space-frequency block coding basedtransmit diversity (SFTD) data is provided to both Port 1 and Port 2every cycle.
 9. The apparatus of claim 1, wherein the demodulationengine further comprises: a plurality of demodulation symbol computationdevices; and a plurality of SNR computation devices, wherein eachdemodulation symbol computation device and SNR computation device iscoupled to one of a plurality of output ports.
 10. The apparatus ofclaim 9, wherein an output of a first multiplexer is coupled to a firstdemodulation symbol computation device and a first SNR computationdevice coupled to a first output port and an output of a secondmultiplexer is coupled to a second demodulation symbol computationdevice and a second SNR computation device coupled to a second outputport.
 11. A method for performing demodulation operations, the methodcomprising: establishing a set of one or more control fields; performinga spatial whitening operation on input data; filtering the whitenedinput data using at least one of Minimum Mean Square Estimation (MMSE)or Maximal Ratio Combining (MRC); and selecting the MMSE or MRCfiltering based on the control fields to produce demodulation data fromthe whitened input data.
 12. The method of claim 11, further comprising:receiving configuration information including control data and whiteningchannel estimates from a task list; and performing demodulationaccording to a demodulation scheme on a serial stream of data.
 13. Themethod of claim 12, wherein the stream of data is derived from aMultiple Input Multiple Output (MIMO) signal and MMSE data is providedto output Port 1 and output Port 2 every cycle.
 14. The method of claim11, wherein the output is provided to a plurality of output ports. 15.The method of claim 14, further comprising providing demodulated data toPort 1 and Port 2 signals in alternating cycles for Spatial-DivisionMedium Access (SDMA) operations.
 16. The method of claim 14, furthercomprising providing demodulated data to both Port 1 and Port 2 everycycle, and data from Port 1 and Port 2 signals in post-processing everycycle for Space-time block coding based transmit diversity (STTD) orSpace-frequency block coding based transmit diversity (SFTD) operations.17. The method of claim 11, further comprising: providing data to atleast one port every cycle for MRC operations.
 18. The method of claim11, further comprising: demodulating based on the spatially whitenedinput data and the selected MMSE or MRC filtering; and determining asignal-to-noise ration (SNR) based on channel estimate data and theselected MMSE or MRC filtering.
 19. A computer program product,comprising computer readable medium comprising code for causing acomputer to process communication signals, comprising: instructions toestablish a set of one or more control fields; instructions to perform aspatial whitening operation on input data; instructions to filter thewhitened input data using at least one of Minimum Mean Square Estimation(MMSE) or Maximal Ratio Combining (MRC); and instructions to select theMMSE or MRC filtering based on the control fields to producedemodulation data from the whitened input data.
 20. The computer programproduct of claim 19, further comprising: instructions to receiveconfiguration information including control data and whitening channelestimates from a task list; and instructions to perform demodulationaccording to a demodulation scheme on a serial stream of data.
 21. Thecomputer program product of claim 20, wherein the stream of data isderived from a Multiple Input Multiple Output (MIMO) signal and MMSEdata is provided to output Port 1 and output Port 2 every cycle.
 22. Thecomputer program product of claim 19, wherein the output is provided toa plurality of output ports.
 23. The computer program product of claim22, further comprising instructions to provide demodulated data to Port1and Port 2 signals in alternating cycles for Spatial-Division MediumAccess (SDMA) operations.
 24. The computer program product of claim 22,further comprising instructions to provide demodulated data to both Port1 and Port 2 every cycle, and data from Port 1 and Port 2 signals inpost-processing every cycle for Space-time block coding based transmitdiversity (STTD) or Space-frequency block coding based transmitdiversity (SFTD) operations.
 25. The computer program product of claim19, further comprising: instructions to provide data to at least oneport every cycle for MRC operations.
 26. The computer program product ofclaim 19, further comprising: instructions to demodulate based on thespatially whitened input data and the selected MMSE or MRC filtering;and instructions to determine a signal-to-noise ration (SNR) based onchannel estimate data and the selected MMSE or MRC filtering.
 27. Anapparatus in a wireless communications system, the apparatus comprising:means for establishing a set of one or more control fields; means forperforming a spatial whitening operation on input data; means forfiltering the whitened input data using at least one of Minimum MeanSquare Estimation (MMSE) or Maximal Ratio Combining (MRC); and means forselecting the MMSE or MRC filtering based on the control fields toproduce demodulation data from the whitened input data.
 28. Theapparatus of claim 27, further comprising: means for receivingconfiguration information including control data and whitening channelestimates from a task list; and means for performing demodulationaccording to a demodulation scheme on a serial stream of data.
 29. Theapparatus of claim 28, wherein the stream of data is derived from aMultiple Input Multiple Output (MIMO) signal and MMSE data is providedto output Port 1 and output Port 2 every cycle.
 30. The apparatus ofclaim 27, wherein the output is provided to a plurality of output ports.31. The apparatus of claim 30, further comprising means for providingdemodulated data to Port1 and Port 2 signals in alternating cycles forSpatial-Division Medium Access (SDMA) operations.
 32. The apparatus ofclaim 30, further comprising means for providing demodulated data toboth Port 1 and Port 2 every cycle, and data from Port 1 and Port 2signals in post-processing every cycle for Space-time block coding basedtransmit diversity (STTD) or Space-frequency block coding based transmitdiversity (SFTD) operations.
 33. The apparatus of claim 27, furthercomprising: means for providing data to at least one port every cyclefor MRC operations.
 34. The apparatus of claim 27, further comprising:means for demodulating based on the spatially whitened input data andthe selected MMSE or MRC filtering; and means for determining asignal-to-noise ration (SNR) based on channel estimate data and theselected MMSE or MRC filtering.